Electric circuit interrupting device



March 16, 1954 J, BQDDY 2,672,563

ELECTRIC CIRCUIT INTERRUPTING DEVICE Filed May 28, 1951 INVENTOR. (/OHN Boo/3v ATTORNEYS.

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Patented Mar. 16, 1954 ELECTRIC CIRCUIT INTERRUPTING DEVICE John Boddy, Hayes, England, assignor to Trico- Folberth Limited, Brentford, England, a British ompany Application May 28, 1951, Serial No. 228,627

11 Claims. 1

This invention relates to a device for continuously making and breaking an electric circuit, for example, a circuit containing one or more electric lamps such as is used in a direction indicating device which may be in a vehicle or in a stationary position.

According to the invention, the device comprises a, contact-carrying member which tends to set itself in a predetermined position but is restrained from occupying this position by a 0011- ductor, or conductors, which, when connected in the electrical circuit to be interrupted, becomes heated and expands and thereby allows the contact-carrying member to move and occupy the said predetermined position.

The movement of the stressed member is used to interrupt the circuit, or short-circuit the conductor, which then cools and restores the contactcarrying member to its restrained position, whereupon the cycle of operations is repeated.

The arrangement may be such that, when no current is flowing through the conductor, a contact on the contact-carrying member is separa"- ed from a fixed contact, and, when the device is connected in the circuit, the current flows through the conductor which is thereby heated and allows the two contacts to close whereby the conductor is short-circuited. Then, if the conductor is of a suitable resistance, or a resistance is inserted in series or parallel with it, the lamp connected in circuit with the device will be alternately flashed on and off, or will be alternately brightly and dimly illuminated. Preferably, the resistance is adjustable, so that by adjusting the resistance the brightness of the lamps when dimmed, or the rate of flash may be varied.

According to a preferred construction, the stressed member consists of a strip of resilient conducting material having a slot extending at a small distance from each of its longitudinal edges so as to divide the strip into three parallel narrower strips, the ends of which are connected together. The two outer strips may then be slightly shortened, for example, by forming a transverse indentation therein, so that the central strip portion is stressed and tends to become bowed either convexly or concavely with respect to the outer strips. The central strip which carries an electric contact is then held by the conductor in a positionother than that in which it tends to set itself.

In order that the invention may be easily un derstood and readily carried into effect, a circuitinterrupting device according to the invention is illustrated by way of example in the accompany ing drawings, in which Figure 1 is a side elevation partly in section through the casing of the device;

Figure 2 is a plan of Figure 1, the casing being in section;

Figure 3 is a perspective view of the complete device,

Figure 4 is an end elevation with the end of the casing removed;

Figure 5 is a plan'of an alternative arrangement, and

Figure 6 is a circuit diagram.

Referring to the drawing, the device comprises an insulating base I, of which the centre portion of the upper surface is slightly recessed as shown at 2. A strip 3 of flexible conducting material, for example phosphor bronze, extends across the recessed portion 2.

The strip 3 is formed with two longitudinal slots i and 5 which extend over the greater part of the length of the strip, but terminate short of the ends of the strip. The strip 3 is thereby divided into three narrower parallel strips 3a, 3b and 30. At one end, namely the left end in Figures 1 and 2, an ear I is struck up out of the strip beyond the ends of the slots,

and this end of the strip is fixed to the base I by means of a screw 9, which passes through the hole 8 formed on striking up the ear, the head of the screw bearing against the upper sur face of the end of the strip. There may be a small clearance between the head of the screw 9 and the strip which clearance may be varied by adjusting the screw 9, and it has been found in practice that the adjustment of the screw increases or decreases the force required to make and break contact, therebyaltering the rate of flash. The other end of the strip 3 beyond the slots 4 and 5 rests on the unrecessed right-hand end of the base portion I. This end of. the strip 3 is covered by a plate I0 of insulating material and on this is super-imposedan arm H of conducting material, which extends to about the middle of the slotted portion of the strip 3. One end of the arm H is bent downwardly, as shown at [2, and is secured to the base I by a screw I3. The bent end I2 is inclined at a. small angle to the end face of the base I, and, as has been found by experiment, adjustment of the screw I3 does not only affect the rate of make and break of contact but also the duration of the On and off periods. A further screw it passes through the arm II, the plate It and the strip 3 and is provided with a nut l5 which bears against the bottom of a recess [6 in the underside-0f the base I. This screw may serve as a terminal and 2') which is struck up out of the material of the:

arm II. The wire I8 is connected under tension between the ear 1 and the -insulatorw; -wherebythe centre strip 3a is stressedao a greaterlextent than the outer strip 31) width. Th t n 14s.;

preferably of thinner gauge material than'the ear 20, so as to ensure that itisthe ear I which is movable under the influence cf -thvwli'er The wire I8 is connected in series iwithAauresistance 2| which is electrically connected to the .SQIBW. Mandmavhe. read lved stedto suia circuit in whih tiie device. is; towbe connected.

'.he arm. I a 'the. pa Whi tlestrip i'i a v mamas-n and 23" which t'end'to closeowihg ,to 111 .16. stre s t str p. 3a. ut. arespacedia sh r distance apartwhen the'wire IB is under tension. The deviceds enclosed in a easel! havin'ga clamp fi'by which itmay bejsecured in position. As shown in Figure 3, a.. hand;le3I"'by:which..the

resistance 21 maybe adjusted protrudes through a slot in the casing,

In the modificationshown ini'Fi'glure instead of tlie flil Filmore. isused adisc 1 170m which two segments fare-f cut out, I so. as to leave ,a central striprfl -joified to." an annularpart 34 whichds --secured*by 'meansof'screws" 35* to the"base. In other respects thearrangement issimilar to that previously described.

3*T lre device cpnnectedffin the circuit't be in theimanner-shoivn in-1"lgure 6'. "A *Wpi current-26 is-connected to the terminal suswmn is-in eleetricalfconnection.with the arrn i lland the wired 8, or,jas SYlOWlifill" Figures 11 and tmaybezconnectedgby a gleajd f 2 I. toithe screw -H-whichis incontact with tlrie arm H. A lead zfflis takenfrom thascrew vorzfrom'the termirial-'11: both. of "which are in electrical contact "with?the-strip 3;fto: tlie flamp for; lamps to be a e :"Asjth w 'f i fEisure the leadini'fi "taken-to;adolibl-tiirow switch LI-2o that for i in *operationf when-tire current? is switched on, it m'st flows -through l the wire 18; resitance 2'] Ether-strip 3a and tl'ie lampsiileifwhich.may be i; 'yfd'lnflyilhiminatedior unilluminatedjjdependingpn theiresistance 21 ,"so that thei'wire '[b ecomes lieat- ;ed. -""As- "soon asjthisihappens the stress on;the "Sc-is *rel'axed gan dflthe strip.E 3a flexes and "establishe .Qontact; between h the contacts 2 2 fj-and j28"'wliereby; the wire [8* and. resistance. 2 I are :short circnited' and the lamp directly,v con- -=neeted"to;-the" source of currentjand" are; brightly *illllminatedi The Wl1'6".th8n cools, the. striplila assumesdts-former position" and" breaks the conneetion betweemthe"contacts "and also that tlie la-mp is again connected in series' with the Mim -I wand resistance 2 I, andtheqcycie-ofbperationist-repeated? flhdrres fitance man also be-hseddonadjust- 7 In some cases, the strips 3!) and 30 may be slightly shortened, as by forming an indentation in each of them in order to increase the stress on the strip 3a, or, alternatively, the centre strip 3a may be stretched relatively to the strips 3b and 30.

Various modifications may be made. The contact-carrying 1 member 1 :stnipultra:1119 be bimetallicgbntE-itii's preierredito. make itlof a material, such as phosphor-bronze, which is not at- .rected to any considerable extent by variations in temperature.

1 obviouslyg insiiead of a single strip 3a, a num- -.ber. of. such-. strips..could be provided by increasing thenumbemotaldts, and each strip could carry a contact.

A tension spring or other elastic material may be connected between the ear I and, for example, a. rotatable shaft, so that the part 3a is stressed both by the spring and by the wire thus providing further means of adjustment. ,The adjustableresistance II is, then no .longer, necessary The distance .byv-wliich the. .contact21iis.spaced "from the'contact'n; when tlie.,Wire;}jl'8Y,is.un-

' rmayibe adiustedby'meansronexa me,

of a screw which is screwediiitotlielbottomof the base I. and. bears againsttthei sttinQSiaLthus 7 giving another; means .of) adiii's'tment iorthe, rate of'make and break.

In-the' constructions ,abovei,.describ.ed;,thej con.- ta'ct-carrying meniblersare; in ftlie' form ofls'ubstantially fiatplates or discs. ",TliejiHVelitibDJ not restricted thereto;'and thepontacti-carrying member ma y"be"bent',for examplejinto ,uj-shape.

or intosteppe'd' form.

The device isnot .llmite'dzi'n its application to the flashing on? andofi" .of Lielectric. lamps,',,and the variation in the j flow'j ofl current;- prddiicsd may be used for other purposes. J For example. the device may be." used iniconjunctionmthp solenoid coil. of; a vehicle 'directionjindicatonnm only to flash: the lamp in theyirrdicatfor but alsoto continuously jraise andflowerlthefarm above. and below the outstretchedbr indicatin'glpositlonn I claim? 1. An electric" circuit inteiruptingidevice comp n a base; aizstrlp' f' illenticonducting material mounted at? its ends .on .jsaidibase, means n ral with" interconnectin the ends or .said strip urging said tr1p,tto occ,upy almfed'etermined position, L a ,j conductor attached it'ogsaid strip. by which said strip 1 is .restrainedj oeu v ne said position, (and-Fa fixe contact with which said strip: engages when. said conductor. is heatedby the passage of "current.

2. An electric circuit ,intfel' tuptins.,.devic,e. as

claimed in claim 1, inwhien saidstiinandfsaid integral means are vi'ormediby cuttinatwo' longitudinal slots in aipiece of sheet material, soas .to form threestripsithe'ends of which areconnecte'd together.

3. An electricpircuit. interrupting .device..as

claimed in claim 1; in whicli saidi's'trip integral means are formed by. cutting, two..-;segments iromanisc'of sheet'materiahsoasid form an annulus with. a 1 diamet'ral strip connected thereto.

.4. An electric. circuittintermptlhgs device;co nprising .a base, a. contact-.carming member. tendingto ,setlitselflin. apredetermined position. said contact-carrying member cqmprisingyasstrip of resilient material mounted ,atl. its ends., onhsaid means integral with -.-and;- n er 01meti8 theends of .sanstrmmrainc ms rimtomm .laidpesitioma oendwtowwltlrwhhhsseidrmemher is restrained from occupying said position, an ad ustable resistance in series with said conductor, and a fixed contact with which the contact of said contact-carrying member engages when said conductor is heated by the passage of current.

5. An electric circuit interrupting device comprising a base, a contact-carrying member tending to set itself in a predetermined position, said contact-carrying member comprising a strip of resilient material mounted at its ends on said base, means integral with and interconnecting the ends of said strip urging said strip to occupy said position, a conductor with which said member is restrained from occupying said position, an adjustable resistance in circuit with said conductor and adapted to vary the combined resistance of said conductor and said resistance, and a fixed contact with which the contact of said contact-carrying member engages when said conductor is heated by the passage of current.

6. An electric circuit interrupting device comprising a contact member tending to set itself in a predetermined position, said contact member comprising a strip of resilient conducting material and means integral with and interconnecting the ends of said strip urging said strip to occupy said position, a conductor by which said member is restrained from occupying said position, a nexible contact arm with which said contact member makes a contact when said conductor is heated by the passage of current, and means for adjusting the position in which said contact member is held by said conductor comprising an adjustable clamp member at one end of said strip and an ad,ustable anchor for said conductor on said contact arm.

7. An electric circuit interrupting device comprising a base, a strip of resilient conducting material mounted at its ends on said base and having two longitudinal slots dividing said strip into three narrower strips the ends oi which are connected together, a conductor attached to one end of the central of said three strips and to a fixed point and normally under tension therebetween, and a contact member with which said central strip makes contact when said conductor is heated by the passage of current, said conductor being connected in circuit with said central strip and said contact member to be shunted by contact therebetween.

8. An electric circuit interrupting device as claimed in claim '7, in which the two outer strips are shortened relatively to the central strip.

9. An electric circuit interrupting device comprising a base, a contact-carrying member tending to set itself in a predetermined position, said contact-carrying member comprising a strip of resilient material mounted at its ends on said base, means integral with and interconnecting the ends of said strip urging said strip to occupy said position, a conductor with which said member is restrained from occupying said position, an adjustable resistance in parallel with said conductor and adapted to vary the combined resistance of said conductor and said resistance, and a fixed contact with which the contact of said contact-carrying member engages when said conductor is heated by the passage of current.

10. An electric circuit interrupting device comprising an insulating base, a contactor element of resilient metal comprising a strip having two longitudinal slots dividing said strip into a contactor strip and a pair of frame strips the ends of which are connected together, an ear struck from said contactor element in one end portion thereof, an insulating plate superimposed on the other end portion of said contactor element, a flexible contact arm superimposed on said plate and extending therefrom to approximately the center of said contactor strip, said arm and said contactor strip having anormal set in contact with each other, an adjustable screw securing said contactor element to said base through the hole provided by striking said ear from said contactor element, means securing said arm and said plate and said contactor element in superposed relation on said base, said arm having an extension overlapping the end sides of said plate and said base having a normal set at a small angle to said side of said base, an ear struck from said arm and extending approximately in alignment with and oppositely to the direction of said extension and mounting an insulator, an adjustable screw mounted in said side of said base and extending through a hole in said extension and having its head overlapping said extension, and a thermally responsive resistance wire stretched from the contactor element ear to said insulator, said wire being under tension at normal temperatures and arranged to hold said contactor strip clear of said arm when under such tension.

11. An electric circuit interrupting device comprising an insulating base, a contactor element of resilient metal comprising a contactor strip and a pair of frame strips integral with and, interconnecting the ends of said contactor strip, an ear extending from said contactor element in one end portion thereof adjacent one end of said contactor strip, an insulating plate superimposed on the opposite end portion of said contactor element, a flexible contact arm superimposed on said plate and extending therefrom to approximately the center of said contactor strip, said arm and said contactor strip having a normal set in contact with each other, means adjacent said ear of said contactor element securing said contactor element to said base, means securing said arm and said plate and said contactor element in superposed relation on said base, said arm having an extension overlapping the end sides of said plate said base and having a normal set at a small angle to said side of said base, an ear struck from said arm and extending approximately in alignment with and oppositely to the direction of said extension and mounting an insulator, an adjustable screw mounted in said side of said base and extending through a hole in said extension and having its head overlapping said extension, and a thermally responsive resistance wire stretched from the contactor element ear to said insulator, said wire being under tension at normal temperatures and arranged to hold said contactor strip clear of said arm when under such tension.

JOHN BODDY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 499,425 Haskins June 13, 1893 2,074,345 Schmidinger Mar. 23, 1937 2,133,309 Schmidinger Oct. 18, 1938 2,225,086 Schramm Dec. 17, 1940 2,384,869 Zuckermann Sept. 18, 1945 

